Hi all,

I am very happy with the spirit on my other helis except on my Diabolo 800.

Setup is: 800 NHP blades, 120 NHP tail blades, Kosmik and XNOVA.

The heli is flying well except in forward flight. It is not dialed in on the elevator axis.
If you pitch up and down you clearly see kind of shaking - would not call it dolphin effect.

It got a little bit better when switching flight mode from 4 to 6. But any other change did not help so far.

My spirit settings:

http://4dsviewer.spirit-system.com/www/ ... ?_fid=44zs


Any tip appreciated, many thanks,

Andreas

Hi,

can you tell me what servos you are using?

what you are describing is quite unusual.
First I recommend to verify if servo centers are good.

In the software you can enable Subtrim (tuning) and then you can check, if all servo arms are exactly at the center/perpendicular (at least how you can verify with eyes).
If they are in center, you can verify if the swashplate is exactly in the horizontal position.

If so, then you can check if there is really 0° between main blades (all these tests with Subtrim (tuning) enabled).

What can make a difference is Elevator Filter - for such big helicopters value of 4 might be necessary. Pitchup compensation can be 0 for now.

_________________
Spirit System developer

Hi,

so did lots of testing last weekend.

First to answer your questions:
Servos:
swashplate: BK DS-7001HV
tail: futaba 276 sv

I verified the mechanical setup - so CG correct, 90° correct and SP leveled.

What really changed the behaviour tremendously was increasing up the head gain to 85% (I know you recommend only 80).
So best seetings currently http://4dsviewer.spirit-system.com/www/ ... ?_fid=lfa0

The effect still shows up in FFF but only if I *reduce* Pitch - nose goes down - hope you have ideas, as the huge change kept me very optimistic to get this fixed.


Thanks,
Andreas

Can you by chance try to decrease BEC voltage to at least 6.6V?

I am not sure if this is the case, but BK/RJX servos, especially 700X series are very prone to noise issues. So then it can oscillate in the flight very quickly or not hold when it should. Decreasing voltage to 6.6V or less can solve the problem.
Usually the problem occur, because servo cables are partially cutted in the place, where a rubber grommet is. So there is a contact with aluminium enclosure.
You can verify it also by multimeter - there should be no resistance between enclosure (bolts) and cables.
I know many cases like this, so it is better to exclude this problem first. This is also why I asked for the servos.

_________________
Spirit System developer

I did a testflight today. I decreased BEC voltage to 6,4V. No change in behaviour, also no strange behaviour overall.
Having that said, I reduced "elevator filter" and "pitchup compensation" to zero.
This made a very visible change, the nose down tendency when reducing pitch im FFF went nearly away.
So what in the end really made the difference was, increasing headgain to 85%.

As max 80% is recommended - is this value nevertheless ok? Should there be zero visible nose/elevator "shake" when reducing pitch - or is that normal with that size of helicopter?

many thanks for your help,

Andreas

That is great.

Thank you for the info.

For bigger helicopters cyclic gain can be even higher, so it is not problem. If you cant see any negative impact, you can even increase it.
It depends on the model itself. Some will need higher gains, some will fly well even with 30%.
With bigger helicopters it is very well visible what helicopter is doing, but it should be possible to completely eliminate any problems.
There is a greater demand for precise settings of the mechanics as any deviation will be visible.
Unit has automatic compensations for pitchup, without it all the problems would be much more visible.

Also different blades can make very noticeable difference. Agressive blades will show more issues, blades such as Edge FBL will improve it.

_________________
Spirit System developer

Finally had some time to test some more.

As already said the effect got *much* less.

I have seen tendency to take "the nose down" - which is clearly visible in turns as well.
A friend mentioned that difference after me flying my Goblin - so the difference to the Diabolo seems very prominent in regards of this effect.
CG checked again so that matches. As you mentioned Pitch up compensation should not be needed, right?

A real pity as in all other maneuvers the heli is perfectly dialed in. So a bit clueless but will keep you posted here once I make some progress.

Will test with alternative blades - I have Maniac 817 at home and will test if I can see a difference.

many thanks again,
Andreas